1. Field of the Invention
The present invention relates to a laser treatment apparatus for irradiating an affected part of a patient's eye with a treatment laser beam.
2. Description of Related Art
For treatment for aftercataract and so on of a patient's eye, there conventionally has been used a laser treatment apparatus (laser operation equipment) for irradiating an affected part of the patient's eye with a treatment laser beam of pulse wave. The apparatus of this kind is designed to vaporize and crush the tissue of the affected part by focusing the treatment laser beam on a desired point (an area to be treated) of the affected part, thereby forming plasma to generate shock waves. Accordingly, the importance is to precisely focus the treatment laser beam on the desired point. For achieving this purpose, there has been known a method of focusing a treatment laser beam on a desired point after irradiating two (or more) visible aiming beams so as to coincide with each other (i.e., to overlap two images of the aiming beams) at the desired point on which the treatment laser beam is to be focused. It is to be noted that the coincidence of two aiming beams at the desired point for the focusing of the treatment laser beam on the desired point is referred hereinafter to as “sighting”.
Moreover, there is a method of shifting a focus point of the treatment laser beam to the coincident point of the aiming beams. In this case, the sighting is also important.
For treatment for retinal diseases, there has been used a laser treatment apparatus (photocoagulation apparatus) for irradiating an affected part of a patient's eye with a treatment laser beam of continuous wave. The apparatus of this type is designed so that a visible aiming beam is irradiated to focus on a desired point which is the same as a focus point of the treatment laser beam to form an image with the minimum spot diameter, whereby the treatment laser beam is precisely focused on the desired point. It is also noted that the focusing of the aiming beam on the desired point to ensure the focusing of the treatment laser beam thereon is also referred to as “sighting”.
The sighting, however, is performed by an operator while observing the coincident state of the two aiming beams (the overlapping condition of the two images of the aiming beams) or the focusing condition of the aiming beam (the spot diameter of the image of the aiming beam) through eyepieces of a microscopic section of the apparatus. This would cause a difficulty for low-skilled operators in judging the propriety of the sighting. Furthermore, differences among operators may be included in determinations about the propriety of the sighting.
During treatment, for example, during sighting of the aiming beams or irradiating of the treatment laser beam, the operator has to observe the patient's eye through the eyepieces of the microscopic section while holding a contact lens by one hand on the patient's eye. Thus, some operators who are for example of short stature must operate and observe in a forced or uncomfortable position.